1. Field of the Invention
This invention relates to a wire inserting method and a wire inserting apparatus in a wire discharge processing. More particularly, the invention relates to a wire inserting method and a wire inserting apparatus that can reliably insert a wire into a plurality of through-holes of a workpiece or workpieces (object to be processed).
2. Description of the Related Art
Wire discharge processing is a technology that arranges a workpiece or workpieces (object to be processed) and an electrode wire in such a manner as to oppose each other with a very small gap between them, applies electric power between them to generate discharge in the very small gap and conducts a precision processing of the workpiece by discharge energy. The wire discharge processing is employed to form an odd-shaped through-hole in a workpiece, for example.
When the wire discharge processing is executed by inserting the electrode wire through the through-hole formed in advance in the workpiece, a wire inserting method is known in the past that jets a liquid such as water to the through-hole and guides and inserts the electrode wire into the through-hole while the electrode wire is carried by this liquid jet stream (Japanese Patent Kokoku No. 04-71647).
However, the method utilizing the liquid jet is not yet free from the following problems. In other words, when one workpiece has a plurality of through-holes or when the electrode wire is inserted through all the through-holes of a plurality of workpieces, positioning of the liquid jetting direction becomes more difficult when the gap between the first through-hole and the last through-hole is greater and when the diameter of the through-holes is smaller. Consequently, the liquid jet is more likely to scatter around the through-holes at the intermediate part due to even a slight positioning error, and it becomes difficult to reliably insert the electrode wire through all the through-holes.